Rotating concentric {37 homogeneous turbulence{38 {0 fabric bag gas cleaner method

ABSTRACT

This invention relates to the application of couette motion caused by centrifugal forces in a rotating concentric &#39;&#39;&#39;&#39;homogeneous turbulence&#39;&#39;&#39;&#39; fabric bag gas cleaner, to provide uniform separation of gaseous, liquid, and solid particulates in a carrier fluid, by adjustable levels of imposed discrete &#39;&#39;&#39;&#39;homogeneous turbulence&#39;&#39;&#39;&#39; established by Taylor circular couette motion with a multiple array of secondary flow cellular vortices in the annulus between the inner perforated cylinder and the outer perforated cylinder, with both cylinders rotating in the same direction. When the outer cylinder rotates in the opposite direction to the inner cylinder, an adjustable level of imposed discrete spiral band of turbulence in a travelling wave, will ripple the fabric bags, will move either up or down in the annulus, and will clean the collected material from the inner surface of the fabric bags.

States Patent [191 Jan. 15, 1974 ROTATING CONCENTRIC HOMOGENEOUSTURBULENCE" FABRIC BAG GAS CLEANER METHOD William Cumming Leith, 7501Latona NE, Seattle, Wash. 98 11 5 22 Filed: Feb. 7, 1972 21 Appl. No.:223,851

[76] Inventor:

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 532,467 l/l94lGreat Britain 55/400 Primary ExaminerBernard Nozick [57] ABSTRACT Thisinvention relates to the application of couette motion caused bycentrifugal forces in a rotating concentric homogeneous turbulencefabric bag gas cleaner, to provide uniform separation of gaseous,liquid, and solid particulates in a carrier fluid, by adjustable levelsof imposed discrete homogeneous turbulence established by Taylorcircular couette motion with a multiple array of secondary flow cellularvortices in the annulus between the inner perforated cylinder and theouter perforated cylinder, with both cy]in ders rotating in the samedirection. When the outer cylinder rotates in the opposite direction tothe inner cylinder, an adjustable level of imposed discrete spiral bandof turbulence in a travelling wave, will ripple the fabric bags, willmove either up or down in the annulus, and will clean the collectedmaterial from the inner surface of the fabric bags.

3 Claims, 4 Drawing Figures FIGURE III PAIENIEUJM 15 19M SHCET 1 CF 2FIGURE I SEE FIGURE III FIGURE E INVENTOR- WW W M PATENTEDJMI 15 1amSHEET 2 CF 2 FIGURE 1:]:

wil "HIE INNER CYLINDER II angular velocily w I.. F Fv OR A RD Em MC UENS CELLULAR VORTICES SPIRAL TURBULENCE LAMINAR FLOW angular velocily (-IO angular velocity OUTER CYLINDER 6 OUTER CYLINDER 6 FIGURE IV INVENTOR(PM ROTATING CONCENTRIC HOMOGENEOUS TURBULENCE FABRIC BAG GAS CLEANERMETHOD PERTINENT PRIOR ART l. C. Orr, Particulate Technology, MacMillanCo,

New York, 1966 2. M.M. Couette, Annals Chim Phys, ser VI, Vol21,

3. 6.1. Taylor, Phil Trans Roy Soc London, ser A, vol

4. D. Coles, J. Fluid Mech, 1965, vol 21, part 3, pp

SUMMARY This present invention consists essentially in the method ofutilizing Taylor circular couette motion caused by centrifugal forces ina rotating concentric homogeneous turbulence fabric bag gas cleaner toprovide uniform separation of gaseous, liquid, and solid particulates ina carrier fluid, by adjustable levels of imposed discrete homogeneousturbulence established by a multiple array of secondary flow cellularvortices in the annulus between the inner perforated cylinder and theouter perforated cylinder, with both cylinders rotating in the samedirection. When the outer cylinder rotates in opposite direction to theinner cylinder, an adjustable level of imposed discrete spiral band ofturbulence in a travelling wave, will ripple the fabric bags, will moveeither up or down in the annulus, and will clean the collected materialfrom the inner surface of the fabric bags.

This invention utilizes the basic functions of a fabric bag gas cleaneras described historically by Orr in reference l; but this inventiondepends on centrifugal forces between rotating concentric cylinders toinitiate couette motion as reported initially by Couette in reference 2;and depends on criteria for hydrodynamic instability as reported byTaylor in reference 3; and depends on regiemes of stabilized couettemotion as given by Coles in reference 4.

This invention utilizes the stabilized boundary layer of couette motionto dampen out non-uniformities in the supply flow of a carrier fluidwith gaseous, liquid, and solid particulates at present in use in fabricbag gas cleaners, which are due to variable levels of steady, random,and cyclic excitation forces initiated by disturbance energy sourcesfrom hydrodynamic origins in the fluid, hydroelastic origins in thestructure, and thermodynamic origins in the pressure-temperatureenvironment.

DESCRIPTION OF DRAWINGS The accompanying drawings illustrate thefollowing detailed specifications:

FIG. I shows a plan view of a rotating concentric homogeneousturbulence" fabric bag gas cleaner 1, with the dirty gas inlet 2, andthe clean gas outlet 3, and the fabric bags 4.

FIG. II shows a front sectional elevation ofa rotating concentrichomogeneous turbulence" fabric bag gas cleaner 1, with the fabric bags 4supported by a frame 5. The fabric bags 4 are nested in the annulusbetween the outer cylinder 6 and the inner cylinder 11. The outerperforated cylinder 6, is supported by a bearing 7, and driven by a gear8, supported by a bearing 9, and a motor 10. An inner perforatedcylinder 11, is supported by bearings 12 and 14, and driven by a shaft13, and a motor 15. The gaseous, liquid, and solid particulates in thedirty inlet gas 2, sweep into the fabric bag 4, where the Taylorcircular couette motion provides a uniform separation by secondary flowcellular vortices, with both cylinders rotating in the same direction.When the outer cylinder rotates in the opposite direction to the innercylinder, a spiral band of turbulence in a travelling wave, will ripplethe fabric bags, will move either up or down, and will remove thecollected material from the fabric bags.

FIG. III is a partial sectional view of the annulus between the twocylinders 6 and 11, showing the multiple array of secondary flowcellular vortices.

FIG. IV shows the specific regieme of stabilized couette motion given byColes in reference 4, with the multiple array of secondary flow cellularvortices when both cylinders turn in the same direction, and the spiralband of turbulence when the outer cylinder rotates in the oppositedirection to the inner cylinder,

DETAILED DESCRIPTION The object of the invention is the application ofcouette motion caused by centrifugal forces in a rotating concentrichomogeneous turbulence fabric bag gas cleaner to provide a laminar flowwith adjustable levels of imposed discrete homogeneous turbulence" inthe radial direction, which promotes the uniform separation of gaseous,liquid, and solid particulates in a carrier fluid, with a multiple arrayof secondary flow cellular vortices in the annulus between theperforated cylinders, with both cylinders rotating in the samedirection. When the outer cylinder rotates in the opposite direction tothe inner cylinder, a spiral band of turbulence in a travelling wave,will ripple the fabric bags, will move either up or down in the annulus,and will clean the collected material from the inner surface of thefabric bags.

The mathematical basis for the present invention is given in references3 and 4, in which an imposed hydrodynamic instability can lead usuallaminar flow to another state of imposed laminar flow, rather than theexpected turbulent flow. In the case ofa rotating concentric homogeneousturbulence" fabric bag gas cleaner, Taylor circular couette motioncaused by centrifugal forces impose a steady secondary flow in theannulus between the two cylinders by establishing a multiple array ofsecondary flow cellular vortices when both cylinders rotate in the samedirection; or it will impose a spiral band of turbulence in a travellingwave, which will ripple the fabric bags, will move either up or down inthe annulus, and will clean the collected material from the innersurface of the fabric bags, when the outer cylinder rotates in theopposite direction to the inner cylinder.

Couette motion between rotating concentric cylinders is well known, butthis invention is related to perforated cylinders with radial flow thruthe perforated cylinders, rather than the usual couette motion withstagnant or longitudinal flow in the annulus between the cylinders.

This invention utilizes the basic functions of a fabric bag gas cleaneras described historically by Orr in reference l; but this inventiondepends on centrifugal forces caused by flow between rotating concentriccylinders to initiate couette motion as reported by Couette in reference2; and depends on the criteria for hydrodynamic instability as reportedby Taylor in reference 3; and depends on the detailed study of variousregiemes of couette motion as given by Coles in reference 4 in which amultiple array of secondary flow cellular vortices is established whenboth cylinders rotate in the same direction, or a spiral band oftubulence is established when the outer cylinder rotates in the oppositedirection to the inner cylinder.

This invention utilizes the stabilized boundary layer of couette motionto dampen out the non-uniformities in the supply flow of a carrier fluidwith gaseous, liquid, and solid particulates at present in use in fabricbag gas cleaners, which are due to variable levels of steady, random,and cyclic excitation forces initiated by disturbance energy sourcesfrom hydrodynamic origins in the fluid, hydroelastic origins in thestructure, and thermodynamic origins in the pressure-temperatureenvironment which are expected from operating transients at startup,emergency shutdown, and maintenence shutdown in metallurgical operationswith particulates of typical metals such as lead, zinc, copper, iron,and uranium.

This invention differs from the usual classical couette motion withstagnant or longitudinal flow between the rotating concentric cylinders,in that this invention utilizes radial flow thru the perforatedcylinders.

This invention is an improvement on present day fabric bag gas cleanershandling a carrier gas polluted with gaseous, liquid, and solidparticulates having nonuniformities in concentration, density, andvelocity produced by the dirty gas jetting into the fabric bag, in

that this invention utilizes a final uniform separation by couettemotion in addition to the usual fabric bag separation.

This invention differs from the usual fabric bag gas cleaner in that auniform separation by couette motion produces an imposed residence timefor uniform separation of gaseous, liquid, and solid particulates in thecarrier fluid.

The rotation speed, the number and diameter of the perforations togetherwith the perforation pattern and percent perforated area can beoptimized for a specific separation of gaseous, liquid, and solidparticulates in a carrier fluid, such as the metallurgical particulatesof lead, zinc, copper, iron, and uranium.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as the following improvements:

1. The method of utilizing Taylor circular couette motion in a fluid toclean a porous filter positioned in the annular area between inner andouter rotary perforated cylinders and rotating said cylinders in opposeddirections to provide a spiral band of turbulence in a travelling wave2. The method of claim 1 further including filtering particulate matterfrom a fluid by passing said fluid through said filter while theperforated cylinders are rotating in the same direction.

3. The method of claim 2 wherein said filter is a bag

2. The method of claim 1 further including filtering particulate matterfrom a fluid by passing said fluid through said filter while theperforated cylinders are rotating in the same direction.
 3. The methodof claim 2 wherein said filter is a bag filter.